Good Morning Steffen,
Excellent question. You’re more than welcome to change the “Read More” text to fit your needs. There are two files you’ll need to alter: index.php and archive.php. In both of them you’ll find Read More
written three times in this section:
<?php if ( of_get_option('content_excerpt') == 'excerpt' ) : ?>
<?php the_excerpt(); ?>
<a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'grassroots' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><span class="more-link"><?php _e('Read More', 'grassroots'); ?></span></a>
<?php else : ?>
<?php if ( ! has_excerpt() ) : ?>
<?php the_content(__('<span class="more-link">Read more</span>', 'grassroots')); ?>
<?php else : ?>
<?php the_excerpt(); ?>
<a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( sprintf( __( 'Permalink to %s', 'grassroots' ), the_title_attribute( 'echo=0' ) ) ); ?>" rel="bookmark"><span class="more-link"><?php _e('Read More', 'grassroots'); ?></span></a>
<?php endif ; // ! has_excerpt ?>
<?php endif ; // if of_get_option = excerpt ?>
You’ll need to preserve the punctuation and other characters that surrounds where it says Read More
but outside of that you can use whatever text you’d like to have there.
If you have any questions or trouble, just let me know.
Have a great day,
Bill